The present invention relates to warning devices, and in particular to a fire detector of the early warning type having integrated circuit components which may economically be manufactured and assembled, and which maintain the sensitivity of the detector to products of combustion substantially constant despite changes in the level of power supplied thereto.
Fire detectors, particularly those of the ionization chamber type, are often used in home and industry to sense the occurrence of combustion. Such devices detect combustion while it is in its incipient stage, and provide a warning well before the combustion reaches an advanced stage. Obviously, these devices are extremely advantageous in protecting life and property from the danger of fire.
The cost of early fire detectors was such that generally only industry could afford the protection they offered. Recent manufacturing techniques, however, using discrete semiconductor devices in the detector circuits, have reduced the cost of detectors to a level where they are now within the purchasing power of a large number of households. Despite such reduction in cost there are, nevertheless, a significant number of households that still cannot afford a fire detector. It is therefore extremely desirable to further reduce the cost of such detectors, without reducing the sensitivity or reliability thereof, to bring the protection they offer within the economic reach of almost all households.